Today, realism in art leads to something called the
physionotrace. The University of Houston's College
of Engineering presents this series about the
machines that make our civilization run, and the
people whose ingenuity created them.

What do you expect from a
picture? Turn that question in the light, and it
gets complicated. Medieval pictures were often
taken from standard sets of images. The same face
might be called St. Peter in one manuscript and
Socrates in another.

A cartoon of Bill Clinton today is equally far from
reality, but it's recognizable because of
systematic exaggeration. An 18th-century portrait
was quite realistic by comparison, although artists
weren't above smoothing over human imperfections.

What we expected from a picture shifted
dramatically around 1500. When we started
illustrating the new printed books, we could show
the same picture to far more people. Suddenly we
had good reason for creating realism in art.

Leonardo da Vinci had little to do with print, but
his whole life revolved around realism. Leonardo
used every means he could muster to expose external
realities. He built camera obscuras and transparent
screens to help capture what the eye saw.

Then Albrecht Dürer took up mechanical means
for making pictures. He used them to create a new
respect for realism in art, and he wrote a book on
those methods. When artists saw that any technician
could reproduce the world literally, it seemed
clear that realism should become a part of their
artistic vision.

After Leonardo and Dürer, a great parade of
perspective instruments, pantographs, and universal
drawing devices marched down through the 16th,
17th, and 18th centuries. Yet art didn't lose its
soul in the process. A lot of that mathematically
inspired art is glorious to see, even if it
remained rooted in a world of palpable reality for
300 years.

A portrait of Thomas Jefferson drives the point
home. It's a compelling, slightly arrogant,
immensely intelligent face -- all the things you'd
expect Jefferson to be. But it was made with the
help of an instrument called a physionotrace.

A physionotrace was a contraption in which you
mounted your subject. You created the image by
tracing him with an eyepiece connected to a
pantograph. It sounded very scientific. It touched
the rational, 18th-century, Jeffersonian mind. This
mechanical Jefferson -- this wholly realistic
Jefferson -- is more like a neighbor or colleague
than the patrician face you see on a nickel.

Then, the same year Jefferson died, a French
inventor made the first photograph. It was an
eight-hour exposure of Paris housetops. After that,
realism became the work of cameramen.

And our expectations underwent another huge change.
Art swiftly returned to the business of recording
not just what the eye saw, but what the mind had
built.

I'm John Lienhard, at the University of Houston,
where we're interested in the way inventive minds
work.

(Theme music)

Kemp, M., The Science of Art. New Haven:
Yale University Press, 1990. See especially Chapter
IV, Machines and Marvels.